Percent of body weight you're pushing in push ups?

Yea, I was wondering this. Anyone have any idea how much percent of your body weight you'd be pushing when you're doing pushups with perfect form? I tried using a scale, and it came out to 140, and I weighed 200 at the time. so that's 70%. But I could do 30 reps, and when I bench, i can only do 140 for 12 reps.

Remember, when you're bench pressing, you won't be able to rep-out like you did doing push-ups, you're using a lot of secondary muscle groups (tris, delts) to push up the bar...

Also, I think it has something to do with "weight distribution." When you perform a push-up, your body weight spans the height and width of your body... when you bench press, the length of the bar, or mass rather, is more centralized, thus the reason why you can't perform as many reps.

Look at the difference between dumbbells and barbells. You can load up both with the same amount of weight, but I guarantee you'll be able to perform more reps with the barbell because the weight is more "evenly" distributed throughout the bar, requiring less stabilizer muscles to support the weight.

Most people are around two thirds (obviously someone that never works out their lower body is going to have a higher percentage). The weight bar has something to do with it as control muscles are needed on the bench.

Also, if you watch the motion of a pushup closely you'll see that it follows more of a declined benchpress's path, which alot of people find themselves to be stronger at than a bench press.

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When lifting weights you have to remember that the 'heaviness' of the weight and dificulty you have moving it is not solely determined by its mass. But it is also determined by how far you are moving that mass. and its final position.

For example, lets say you weight 192 lbs. So exactly 70% of your weight is 135 lbs. Lets also say that you have a ROM of 1 foot on the bench press.

When you are benching, you are moving 135lbs a distance of 1 foot. (work = force *distance) The work you are doing right here is actually what your muscle feels. NOT the force.

For distance, lets assume he has a 5 foot span from feet to hand stance, and he rises 1 foot when he does it. So the distance he moves is D = 1/5X or Y= 0.2X

The force . . . force was tricky. I assumed that body mass increases slightly as you move up the torso. Honestly. This part is actually pretty tricky. So im going to skip the explanation for it. But the force of i modeled as F = 23 + 6x (you can check this by checking to be sure, by taking the integral of this and making sure it is equal to the weight of our person from a range of 0 to 5ft. Since the force of our person is 192lbs)

Hence when you are doing a push-up. You are doing 107.5lbs*ft of work
Compared to when you are doing an actual 135lb, you are doing 135lb*ft of work

So in actuallity, Because your body moves on a pivoting plane. you are really only doing closer to 55% of your body weight (even the scale is telling you that your top half weighs 65-70% of your body weight)